In all cases, if you are being asked to purchase the app again despite having already purchased it, please confirm that you are logged into the store with the same account used to originally purchase it. This is the only way it will recognize that the app has already been previously purchased.
iPhone/iPad
Your purchase is linked to the Apple ID that you originally used to make the purchase. If you login to the App Store using the same Apple ID, the app will show up under the Purchases section and allow you to reinstall it from there. For more information, see here:
https://support.apple.com/en-us/HT201272#apps
Mac
Your purchase is linked to the Apple ID that you originally used to make the purchase. If you login to the Mac App Store using the same Apple ID, the app will show up under the Purchases section and allow you to reinstall it from there. For more information, see here:
https://support.apple.com/en-us/HT201272#apps
Android
Your purchase is linked to the Google Play Store account that you originally used to make the purchase. If you login to the Play Store using the same account, the app will show up under My Apps -> All. Note: because the Play Store allows you to be logged into multiple accounts at the same time, you may need to change which account you're actively using. For more information, see here:
https://support.google.com/googleplay/answer/113410?hl=en
Windows
Your purchase is linked to the license key you received via email when you originally made the purchase. You can reinstall Paprika on your new computer by downloading the installer from here:
https://www.paprikaapp.com/downloads/windows/latest/PaprikaSetup.msi
Once Paprika is installed, you can reactivate it using your existing license key. If you have forgotten your license key, please see this article.